Investigating the Effect of Nano-silver Contained Packaging on the Olivier Salad Shelf-life

Abstract

Convenience food has become an inseparable part of today’s hectic life and its quality, durability, and health level should be highlighted. Food packaging is the most popular way to prevent bacterial spoilage and nutrient loss. Meanwhile, emerging antibacterial packages have shown additional properties in increasing storage time. Here, the effect of using polyethylene packages containing silver nanoparticles with different concentrations (0.02 and 0.04%) on the durability, appearance, microbial, and organoleptic properties of Olivier salad was investigated. In this regard, Olivier salad was packaged in 3 sets of polymer packages containing 0, 0.02 and 0.04% silver nanoparticle. The samples were then under test for 2-, 12-, and 22-day periods where microscopic, microbial, and sensory analyses were conducted. Scanning electron microscope (SEM) was implemented in physical characterization and the silver ions migration from the packages to the sample was measured by atomic adsorption method (AA). In addition, texture, taste, and general acceptance of packaged samples were studied by a 9-point evaluation method and trained panelists and the color and appearance by Image J software. SEM images proved the presence and proper distribution of nanocrystalline structure in the packages. Microbial tests’ results showed that the overall counting of micro-organisms and mold increased with increasing storage time and decreased with increasing nanoparticle concentration in the packages. Also, coliform count decreased in all three packages (containing no, 0.02 and 0.04% silver nanoparticle) with time, and the concentration of nanoparticles in the nano-silver packages had no effect on coliform results. All sensory characteristics were better in samples with silver nanoparticle packages and AA results showed a direct relationship between ion migration and storage time and silver nanoparticle weight fraction. Finally proper curves were fitted over different experimental data and resultant equations were optimized in definite ranges (silver nanoparticle concentration = 0–1000 ppm, time = 0–15 days, total bacteria count = 17,500–14,500,000 cfu/g, Coliform = 0–3300 cfu/g, mold and yeast = 200–2,500,000 cfu/g, taste = 9-65, texture = 11–55, total acceptance = 12–65, color parameter L* = 68.886–95.132, Ag ion migration = 0–10). It was concluded that the antibacterial effect as well as perfect performance in keeping the properties fresh for around 14 days could be accomplished with a concentration of 404.93 ppm for silver nanoparticles.